What is DNS?
In one sentence: Domain Name System: the internet's phone book, turning names into IP addresses.
A little more
Computers find each other by number (an IP address), but people remember names. DNS, the Domain Name System, is a huge shared directory that turns a name like example.com into the right number. Your device asks a DNS resolver, which asks other servers in turn until it finds the answer, then remembers it for a while.
If DNS breaks, websites seem to vanish even though they're still running, because nobody can find their number.
It's a bit like… The contacts list on your phone: you tap a name, and it dials the number for you.
See it in action
- 1What happens when you open a web page?Follow one click from your keyboard to a server and back: DNS, the padlock handshake, HTTP, tunnels and painting the page.6 min · interactive
- 2Anatomy of a web addressPaste any web address and see it taken apart, colour by colour: scheme, host, port, path, query and the fragment that never reaches the server.5 min · interactive